On Wednesday, animal staff supervised a trial run for the cub's mother, Leanne, and cub in the outdoor enclosure. As a very attentive mother, Leanne immediately carried her cub to the safest spot, the lower grass moat area. There they were free to play and run back and forth until the cub was ready to explore. Leanne was so happy to be outside with her baby, she frolicked just like a cub too, zoo staff members said.

"Providing the cub the opportunity to explore the outside world is a significant step in her development," said the zoo's Curator of Carnivores and Primates, Corinne MacDonald. "The cub will build up her strength and confidence watching her mother and she'll learn from her while navigating her new environment. We are thrilled to finally be able to show our tiger cub off outside to all of her fans."

The Sumatran tiger (Panthera tigris) is classified as Critically Endangered by IUCN. The greatest threat to survival is destruction of habitat, followed by poaching. The wild Sumatran tiger population is estimated at less than 400. As of September 2012, there were 74 Sumatran tigers in captivity at 27 accredited institutions of the Association of Zoos and Aquariums in North America.

From the island of Sumatra, off the Malaysian Peninsula, these terrestrial and nocturnal cats inhabit evergreen, swamp and tropical rain forests as well as grasslands. As the smallest of the remaining subspecies of Panthera tigris, the Sumatran tiger is particularly well suited for life in the deep jungle. The fur on the upper parts of its body ranges from orange to reddish-brown, making it darker in color than other tigers. This helps it to hide within its heavily wooded forest habitat. Also unique to this subspecies are distinctly long whiskers, which serve as sensors in the dark, dense underbrush.

Until recently, there were nine subspecies of Panthera tigris. Three subspecies, the Caspian, Bali and Javan tigers, were deemed extinct between the 1940s and 1970s. Estimates to the six remaining subspecies in the wild are as follows (according to IUCN Redlist): Bengal 1,706, Indochinese less than 2,500, Sumatran less than 400, Amur (Siberian) 360, Malayan less than 750, and the South China tiger is thought to be already extinct in the wild. These remaining subspecies are either listed as endangered or critically endangered.

PHOTOS: Sumatran tiger cub on exhibit at SF Zoo

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San Francisco Zoo

An 8-week-old Sumatran tiger cub that was born at the San Francisco Zoo and already has a large fan base will go on exhibit Friday. At 14 pounds, the cub is now strong enough to venture into the outdoor enclosure where zoo visitors can watch her.